The present invention generally relates to an ink jet printer ink set. More specifically, the present invention relates to an ink jet printer ink set that includes one or more colored inks in different concentrations of the same dye and to a method of making ink that has a particular combination of L*, a*, and b* values when printed with the ink jet printer.
Ink jet printing is a commonly used method of recording images on recording materials, such as paper or cloth, by discharging discreet droplets of ink from nozzles of a print head and allowing these droplets to be absorbed by the recording material. Ink jet recording offers opportunities for quiet, high speed, full color printing. Also, images printed with ink jet printers seldom need to be fixed or treated after the ink droplets are absorbed on the recording material.
A number of advances have been made in ink jet printing over the past decade or so. Many of these advances have focused on increasing the contrast and continuity of color in printed images to make the images appear more life-like. Other efforts have focused on increasing the vividness of colors within the image and the range or gamut of different colors seen when viewing the image. Many of these prior efforts also concern the desire to use ink jet printing equipment for reproducing images originally printed with other types of equipment, such as lithographic and flexographic equipment. This is problematic because many of the traditional printing techniques rely on pigmented inks, which produce relatively wide color gamuts. Dyes are generally preferred over pigments for ink jet printing because particulate-free inks are more easily prepared with dyes, as compared to pigments, especially dyes that are highly soluble in the ink vehicle. Particulate-free inks made of highly soluble dyes help eliminate colorant settling and precipitation problems, as well as head clogging and jetted ink deflection problems, during ink jet printing operations.
One standard for pigmented inks is the PANTONE.RTM. traditional color standard that is published by Pantone, Inc. of Carlstadt, N.J. The PANTONE.RTM. traditional color standard is based upon a total of six different colors of pigmented inks. Pantone, Inc. has combined the six different colored inks of the PANTONE.RTM. standard in various combinations to produce an over-all PANTONE.RTM. traditional color gamut of more than 800 different colors. Pantone, Inc. produces two swatch books that include printed samples of the six basic pigmented inks and also include printed samples of the more than 800 different ink colors formed by the various combinations of the six basic pigmented inks. These PANTONE.RTM. swatch books are known as the PANTONE.RTM. Color Selector 1000 For Coated Stock (the "PANTONE.RTM. Color Selector 1000 swatch book") and the PANTONE.RTM. Process Color Imaging Guide (the "PANTONE.RTM. Process Color swatch book"). These PANTONE.RTM. swatch books also list L*, a*, and b* values of the CIELAB color space for each of the more than 800 ink colors reproduced in the two swatch books. These two PANTONE.RTM. swatch books further list the proportions of the six basic pigmented inks that are needed to attain the more than 800 ink colors provided in the two swatch books.
One ink jet printing industry standard for replicating many of the colors attainable using the PANTONE.RTM. traditional color standard, as represented in the PANTONE.RTM. Color Selector 1000 swatch book and the PANTONE.RTM. Process Color swatch book, is the Iris color proofing standard, which is embodied in both the Iris Smart Jet 4012 color proofing system and the Iris Realist color proofing system. The Iris Smart Jet 4012 color proofing system and the Iris Realist color proofing system are each available from Iris Graphics of Bedford, Mass. The Iris color proofing standard relies upon a set of four different dye-based inks of different colors that may be combined through ink jet printing techniques to produce printed images having a particular gamut of different colors.
The Iris color proofing standard has its limits, though, since the Iris standard is only able to reproduce approximately 50% to 60% of the colors attainable using the PANTONE.RTM. traditional color standard, as represented in the PANTONE.RTM. Color Selector 1000 swatch book and the PANTONE.RTM. Process Color swatch book. There is a need to improve upon the capabilities of the Iris color proofing standard and other existing techniques to expand the gamut of colors attainable in images produced by ink jet printing to encompass still more of the colors attainable using the PANTONE.RTM. traditional color standard. Furthermore, expansion of the color gamut attainable by ink jet printing beyond the gamut attained under the PANTONE.RTM. traditional color standard would yield more highly saturated colors for producing vividly colored images never before achieved via ink jet printing.